Electrochemical fabrication methods for producing multilayer structures including the use of diamond machining in the planarization of deposits of material

ABSTRACT

Electrochemical fabrication methods for forming single and multilayer mesoscale and microscale structures are disclosed which include the use of diamond machining (e.g. fly cutting or turning) to planarize layers. Some embodiments focus on systems of sacrificial and structural materials which are useful in Electrochemical fabrication and which can be diamond machined with minimal tool wear (e.g. Ni—P and Cu, Au and Cu, Cu and Sn, Au and Cu, Au and Sn, and Au and Sn—Pb), where the first material or materials are the structural materials and the second is the sacrificial material). Some embodiments focus on methods for reducing tool wear when using diamond machining to planarize structures being electrochemically fabricated using difficult-to-machine materials (e.g. by depositing difficult to machine material selectively and potentially with little excess plating thickness, and/or pre-machining depositions to within a small increment of desired surface level (e.g. using lapping or a rough cutting operation) and then using diamond fly cutting to complete he process, and/or forming structures or portions of structures from thin walled regions of hard-to-machine material as opposed to wide solid regions of structural material.

RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationNos. 60/534,159, and 60/534,183, both filed Dec. 31, 2003. Each of thesereferenced applications is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to the field of electrochemicalfabrication and the associated formation of three-dimensional structures(e.g. microscale or mesoscale structures). In particular, it relates toelectrochemical fabrication processes that utilize diamond machiningduring the planarization of deposited materials.

BACKGROUND OF THE INVENTION

A technique for forming three-dimensional structures (e.g. parts,components, devices, and the like) from a plurality of adhered layerswas invented by Adam L. Cohen and is known as ElectrochemicalFabrication. It is being commercially pursued by Microfabrica Inc.(formerly MEMGen® Corporation) of Burbank, Calif. under the name EFAB™.This technique was described in U.S. Pat. No. 6,027,630, issued on Feb.22, 2000. This electrochemical deposition technique allows the selectivedeposition of a material using a unique masking technique that involvesthe use of a mask that includes patterned conformable material on asupport structure that is independent of the substrate onto whichplating will occur. When desiring to perform an electrodeposition usingthe mask, the conformable portion of the mask is brought into contactwith a substrate while in the presence of a plating solution such thatthe contact of the conformable portion of the mask to the substrateinhibits deposition at selected locations. For convenience, these masksmight be generically called conformable contact masks; the maskingtechnique may be generically called a conformable contact mask platingprocess. More specifically, in the terminology of Microfabrica Inc.(formerly MEMGen® Corporation) of Burbank, Calif. such masks have cometo be known as INSTANT MASKS™ and the process known as INSTANT MASKING™or INSTANT MASK™ plating. Selective depositions using conformablecontact mask plating may be used to form single layers of material ormay be used to form multi-layer structures. The teachings of the '630patent are hereby incorporated herein by reference as if set forth infull herein. Since the filing of the patent application that led to theabove noted patent, various papers about conformable contact maskplating (i.e. INSTANT MASKING) and electrochemical fabrication have beenpublished:

-   -   (1) A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P.        Will, “EFAB: Batch production of functional, fully-dense metal        parts with micro-scale features”, Proc. 9th Solid Freeform        Fabrication, The University of Texas at Austin, p161, August        1998.    -   (2) A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P.        Will, “EFAB: Rapid, Low-Cost Desktop Micromachining of High        Aspect Ratio True 3-D MEMS”, Proc. 12th IEEE Micro Electro        Mechanical Systems Workshop, IEEE, p244, January 1999.    -   (3) A. Cohen, “3-D Micromachining by Electrochemical        Fabrication”, Micromachine Devices, March 1999.    -   (4) G. Zhang, A. Cohen, U. Frodis, F. Tseng, F. Mansfeld, and P.        Will, “EFAB: Rapid Desktop Manufacturing of True 3-D        Microstructures”, Proc. 2nd International Conference on        Integrated MicroNanotechnology for Space Applications, The        Aerospace Co., April 1999.    -   (5) F. Tseng, U. Frodis, G. Zhang, A. Cohen, F. Mansfeld, and P.        Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal        Microstructures using a Low-Cost Automated Batch Process”, 3rd        International Workshop on High Aspect Ratio MicroStructure        Technology (HARMST'99), June 1999.    -   (6) A. Cohen, U. Frodis, F. Tseng, G. Zhang, F. Mansfeld, and P.        Will, “EFAB: Low-Cost, Automated Electrochemical Batch        Fabrication of Arbitrary 3-D Microstructures”, Micromachining        and Microfabrication Process Technology, SPIE 1999 Symposium on        Micromachining and Microfabrication, September 1999.    -   (7) F. Tseng, G. Zhang, U. Frodis, A. Cohen, F. Mansfeld, and P.        Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal        Microstructures using a Low-Cost Automated Batch Process”, MEMS        Symposium, ASME 1999 International Mechanical Engineering        Congress and Exposition, November, 1999.    -   (8) A. Cohen, “Electrochemical Fabrication (EFABTM)”, Chapter 19        of The MEMS Handbook, edited by Mohamed Gad-EI-Hak, CRC Press,        2002.    -   (9) Microfabrication—Rapid Prototyping's Killer Application”,        pages 1-5 of the Rapid Prototyping Report, CAD/CAM Publishing,        Inc., June 1999.

The disclosures of these nine publications are hereby incorporatedherein by reference as if set forth in full herein.

The electrochemical deposition process may be carried out in a number ofdifferent ways as set forth in the above patent and publications. In oneform, this process involves the execution of three separate operationsduring the formation of each layer of the structure that is to beformed:

-   -   1. Selectively depositing at least one material by        electrodeposition upon one or more desired regions of a        substrate.    -   2. Then, blanket depositing at least one additional material by        electrodeposition so that the additional deposit covers both the        regions that were previously selectively deposited onto, and the        regions of the substrate that did not receive any previously        applied selective depositions.    -   3. Finally, planarizing the materials deposited during the first        and second operations to produce a smoothed surface of a first        layer of desired thickness having at least one region containing        the at least one material and at least one region containing at        least the one additional material.

After formation of the first layer, one or more additional layers may beformed adjacent to the immediately preceding layer and adhered to thesmoothed surface of that preceding layer. These additional layers areformed by repeating the first through third operations one or more timeswherein the formation of each subsequent layer treats the previouslyformed layers and the initial substrate as a new and thickeningsubstrate.

Once the formation of all layers has been completed, at least a portionof at least one of the materials deposited is generally removed by anetching process to expose or release the three-dimensional structurethat was intended to be formed.

The preferred method of performing the selective electrodepositioninvolved in the first operation is by conformable contact mask plating.In this type of plating, one or more conformable contact (CC) masks arefirst formed. The CC masks include a support structure onto which apatterned conformable dielectric material is adhered or formed. Theconformable material for each mask is shaped in accordance with aparticular cross-section of material to be plated. At least one CC maskis needed for each unique cross-sectional pattern that is to be plated.

The support for a CC mask is typically a plate-like structure formed ofa metal that is to be selectively electroplated and from which materialto be plated will be dissolved. In this typical approach, the supportwill act as an anode in an electroplating process. In an alternativeapproach, the support may instead be a porous or otherwise perforatedmaterial through which deposition material will pass during anelectroplating operation on its way from a distal anode to a depositionsurface. In either approach, it is possible for CC masks to share acommon support, i.e. the patterns of conformable dielectric material forplating multiple layers of material may be located in different areas ofa single support structure. When a single support structure containsmultiple plating patterns, the entire structure is referred to as the CCmask while the individual plating masks may be referred to as“submasks”. In the present application such a distinction will be madeonly when relevant to a specific point being made.

In preparation for performing the selective deposition of the firstoperation, the conformable portion of the CC mask is placed inregistration with and pressed against a selected portion of thesubstrate (or onto a previously formed layer or onto a previouslydeposited portion of a layer) on which deposition is to occur. Thepressing together of the CC mask and substrate occur in such a way thatall openings, in the conformable portions of the CC mask contain platingsolution. The conformable material of the CC mask that contacts thesubstrate acts as a barrier to electrodeposition while the openings inthe CC mask that are filled with electroplating solution act as pathwaysfor transferring material from an anode (e.g. the CC mask support) tothe non-contacted portions of the substrate (which act as a cathodeduring the plating operation) when an appropriate potential and/orcurrent are supplied.

An example of a CC mask and CC mask plating are shown in FIGS. 1A-1C.FIG. 1A shows a side view of a CC mask 8 consisting of a conformable ordeformable (e.g. elastomeric) insulator 10 patterned on an anode 12. Theanode has two functions. FIG. 1A also depicts a substrate 6 separatedfrom mask 8. One is as a supporting material for the patterned insulator10 to maintain its integrity and alignment since the pattern may betopologically complex (e.g., involving isolated “islands” of insulatormaterial). The other function is as an anode for the electroplatingoperation. CC mask plating selectively deposits material 22 onto asubstrate 6 by simply pressing the insulator against the substrate thenelectrodepositing material through apertures 26 a and 26 b in theinsulator as shown in FIG. 1B. After deposition, the CC mask isseparated, preferably non-destructively, from the substrate 6 as shownin FIG. 1C. The CC mask plating process is distinct from a“through-mask” plating process in that in a through-mask plating processthe separation of the masking material from the substrate would occurdestructively. As with through-mask plating, CC mask plating depositsmaterial selectively and simultaneously over the entire layer. Theplated region may consist of one or more isolated plating regions wherethese isolated plating regions may belong to a single structure that isbeing formed or may belong to multiple structures that are being formedsimultaneously. In CC mask plating as individual masks are notintentionally destroyed in the removal process, they may be usable inmultiple plating operations.

Another example of a CC mask and CC mask plating is shown in FIGS.1D-1F. FIG. 1D shows an anode 12′ separated from a mask 8′ that includesa patterned conformable material 10′ and a support structure 20. FIG. 1Dalso depicts substrate 6 separated from the mask 8′. FIG. 1E illustratesthe mask 8′ being brought into contact with the substrate 6. FIG. 1Fillustrates the deposit 22′ that results from conducting a current fromthe anode 12′ to the substrate 6. FIG. 1G illustrates the deposit 22′ onsubstrate 6 after separation from mask 8′. In this example, anappropriate electrolyte is located between the substrate 6 and the anode12′ and a current of ions coming from one or both of the solution andthe anode are conducted through the opening in the mask to the substratewhere material is deposited. This type of mask may be referred to as ananodeless INSTANT MASK™ (AIM) or as an anodeless conformable contact(ACC) mask.

Unlike through-mask plating, CC mask plating allows CC masks to beformed completely separate from the fabrication of the substrate onwhich plating is to occur (e.g. separate from a three-dimensional (3D)structure that is being formed). CC masks may be formed in a variety ofways, for example, a photolithographic process may be used. All maskscan be generated simultaneously, prior to structure fabrication ratherthan during it. This separation makes possible a simple, low-cost,automated, self-contained, and internally-clean “desktop factory” thatcan be installed almost anywhere to fabricate 3D structures, leaving anyrequired clean room processes, such as photolithography to be performedby service bureaus or the like.

An example of the electrochemical fabrication process discussed above isillustrated in FIGS. 2A-2F. These figures show that the process involvesdeposition of a first material 2 which is a sacrificial material and asecond material 4 which is a structural material. The CC mask 8, in thisexample, includes a patterned conformable material (e.g. an elastomericdielectric material) 10 and a support 12 which is made from depositionmaterial 2. The conformal portion of the CC mask is pressed againstsubstrate 6 with a plating solution 14 located within the openings 16 inthe conformable material 10. An electric current, from power supply 18,is then passed through the plating solution 14 via (a) support 12 whichdoubles as an anode and (b) substrate 6 which doubles as a cathode. FIG.2A, illustrates that the passing of current causes material 2 within theplating solution and material 2 from the anode 12 to be selectivelytransferred to and plated on the cathode 6. After electroplating thefirst deposition material 2 onto the substrate 6 using CC mask 8, the CCmask 8 is removed as shown in FIG. 2B. FIG. 2C depicts the seconddeposition material 4 as having been blanket-deposited (i.e.non-selectively deposited) over the previously deposited firstdeposition material 2 as well as over the other portions of thesubstrate 6. The blanket deposition occurs by electroplating from ananode (not shown), composed of the second material, through anappropriate plating solution (not shown), and to the cathode/substrate6. The entire two-material layer is then planarized to achieve precisethickness and flatness as shown in FIG. 2D. After repetition of thisprocess for all layers, the multi-layer structure 20 formed of thesecond material 4 (i.e. structural material) is embedded in firstmaterial 2 (i.e. sacrificial material) as shown in FIG. 2E. The embeddedstructure is etched to yield the desired device, i.e. structure 20, asshown in FIG. 2F.

Various components of an exemplary manual electrochemical fabricationsystem 32 are shown in FIGS. 3A-3C. The system 32 consists of severalsubsystems 34, 36, 38, and 40. The substrate holding subsystem 34 isdepicted in the upper portions of each of FIGS. 3A to 3C and includesseveral components: (1) a carrier 48, (2) a metal substrate 6 onto whichthe layers are deposited, and (3) a linear slide 42 capable of movingthe substrate 6 up and down relative to the carrier 48 in response todrive force from actuator 44. Subsystem 34 also includes an indicator 46for measuring differences in vertical position of the substrate whichmay be used in setting or determining layer thicknesses and/ordeposition thicknesses. The subsystem 34 further includes feet 68 forcarrier 48 which can be precisely mounted on subsystem 36.

The CC mask subsystem 36 shown in the lower portion of FIG. 3A includesseveral components: (1) a CC mask 8 that is actually made up of a numberof CC masks (i.e. submasks) that share a common support/anode 12, (2)precision X-stage 54, (3) precision Y-stage 56, (4) frame 72 on whichthe feet 68 of subsystem 34 can mount, and (5) a tank 58 for containingthe electrolyte 16. Subsystems 34 and 36 also include appropriateelectrical connections (not shown) for connecting to an appropriatepower source for driving the CC masking process.

The blanket deposition subsystem 38 is shown in the lower portion ofFIG. 3B and includes several components: (1) an anode 62, (2) anelectrolyte tank 64 for holding plating solution 66, and (3) frame 74 onwhich the feet 68 of subsystem 34 may sit. Subsystem 38 also includesappropriate electrical connections (not shown) for connecting the anodeto an appropriate power supply for driving the blanket depositionprocess.

The planarization subsystem 40 is shown in the lower portion of FIG. 3Cand includes a lapping plate 52 and associated motion and controlsystems (not shown) for planarizing the depositions.

Another method for forming microstructures from electroplated metals(i.e. using electrochemical fabrication techniques) is taught in U.S.Pat. No. 5,190,637 to Henry Guckel, entitled “Formation ofMicrostructures by Multiple Level Deep X-ray Lithography withSacrificial Metal layers”. This patent teaches the formation of metalstructure utilizing mask exposures. A first layer of a primary metal iselectroplated onto an exposed plating base to fill a void in aphotoresist, the photoresist is then removed and a secondary metal iselectroplated over the first layer and over the plating base. Theexposed surface of the secondary metal is then machined down to a heightwhich exposes the first metal to produce a flat uniform surfaceextending across the both the primary and secondary metals. Formation ofa second layer may then begin by applying a photoresist layer over thefirst layer and then repeating the process used to produce the firstlayer. The process is then repeated until the entire structure is formedand the secondary metal is removed by etching. The photoresist is formedover the plating base or previous layer by casting and the voids in thephotoresist are formed by exposure of the photoresist through apatterned mask via X-rays or UV radiation.

Even though electrochemical fabrication as taught and practiced to date,has greatly enhanced the capabilities of microfabrication, and inparticular added greatly to the number of metal layers that can beincorporated into a structure and to the speed and simplicity in whichsuch structures can be made, room for enhancing the state ofelectrochemical fabrication exists.

SUMMARY OF THE INVENTION

It is an object of some embodiments of the invention to provideelectrochemical fabrication processes with enhanced capabilities.

It is an object of some embodiments of the invention to provide morerapid planarization of deposited materials during multi-layerelectrochemical fabrication of structures.

It is an object of some embodiments of the invention to provide enhancedand/or more reliable surface finish of planarized materials.

It is an object of some embodiments of the invention to provide enhancedelectrochemical fabrication embodiments that can reliably and efficientmake use of fly cutting to planarize deposited materials.

Other objects and advantages of various embodiments of the inventionwill be apparent to those of skill in the art upon review of theteachings herein. The various embodiments and aspects of the invention,set forth explicitly herein or otherwise ascertained from the teachingsherein, may address one or more of the above objects alone or incombination, or alternatively may address some other object of theinvention ascertained from the teachings herein. It is not necessarilyintended that all objects be addressed by any single embodiment oraspect of the invention even though that may be the case with regard tosome embodiments and aspects.

In a first aspect of the invention, a process for forming a multilayerthree-dimensional structure, including: (a) forming and adhering a layerof material to a previously formed layer and/or to a substrate, whereinthe layer comprises a desired pattern of at least one material, whereinone or more contact pads exist on the substrate or on a previouslyformed layer; (b) subjecting the at least one material to aplanarization operation which comprises diamond machining (c) repeatingthe forming and adhering of operation (a) one or more time to form thethree-dimensional structure from a plurality of adhered layers.

In a second aspect of the invention, the process of the preceding aspectwherein the planarization operation includes at least one lappingoperation or rough cutting operation that brings height of deposition toa level which is closer to that of the final desired level and afterwhich the diamond machining operation brings the level of the depositedmaterials to a level that is within a defined tolerance of a desiredlevel.

Further aspects of the invention will be understood by those of skill inthe art upon reviewing the teachings herein. Other aspects of theinvention may involve apparatus that can be used in implementing one ormore of the method aspects of the invention. These other aspects of theinvention may provide various combinations of the aspects presentedabove or of embodiments presented hereafter as well as provide otherconfigurations, structures, functional relationships, and processes thathave not been specifically set forth above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C schematically depict side views of various stages of a CCmask plating process, while FIGS. 1D-G schematically depict a side viewsof various stages of a CC mask plating process using a different type ofCC mask.

FIGS. 2A-2F schematically depict side views of various stages of anelectrochemical fabrication process as applied to the formation of aparticular structure where a sacrificial material is selectivelydeposited while a structural material is blanket deposited.

FIGS. 3A-3C schematically depict side views of various examplesubassemblies that may be used in manually implementing theelectrochemical fabrication method depicted in FIGS. 2A-2F.

FIGS. 4A-4I schematically depict the formation of a first layer of astructure using adhered mask plating where the blanket deposition of asecond material overlays both the openings between deposition locationsof a first material and the first material itself.

FIG. 5A provides a flowchart of an electrochemical fabrication processthat may be used in practicing some embodiments of the invention.

FIGS. 5B-5I provide block diagrams of operations that may be used duringthe formation of a single layer of a structure or during the formationof each of a plurality of layers of a multi-layer structure according tofirst through eighth embodiments of the invention where the outlinedoperations may be used as operations on in the process of FIG. 5A forthe formation of some or all layers of the structures.

FIG. 6 provides a block diagram of a ninth embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

FIGS. 1A-1G, 2A-2F, and 3A-3C illustrate various features of one form ofelectrochemical fabrication that are known. Other electrochemicalfabrication techniques are set forth in the '630 patent referencedabove, in the various previously incorporated publications, in variousother patents and patent applications incorporated herein by reference,still others may be derived from combinations of various approachesdescribed in these publications, patents, and applications, or areotherwise known or ascertainable by those of skill in the art from theteachings set forth herein. All of these techniques may be combined withthose of the various embodiments of various aspects of the invention toyield enhanced embodiments. Still other embodiments may be derived fromcombinations of the various embodiments explicitly set forth herein.

FIGS. 4A-4I illustrate various stages in the formation of a single layerof a multi-layer fabrication process where a second metal is depositedon a first metal as well as in openings in the first metal where itsdeposition forms part of the layer. In FIG. 4A, a side view of asubstrate 82 is shown, onto which patternable photoresist 84 is cast asshown in FIG. 4B. In FIG. 4C, a pattern of resist is shown that resultsfrom the curing, exposing, and developing of the resist. The patterningof the photoresist 84 results in openings or apertures 92(a)-92(c)extending from a surface 86 of the photoresist through the thickness ofthe photoresist to surface 88 of the substrate 82. In FIG. 4D, a metal94 (e.g. nickel) is shown as having been electroplated into the openings92(a)-92(c). In FIG. 4E, the photoresist has been removed (i.e.chemically stripped) from the substrate to expose regions of thesubstrate 82 which are not covered with the first metal 94. In FIG. 4F,a second metal 96 (e.g., silver) is shown as having been blanketelectroplated over the entire exposed portions of the substrate 82(which is conductive) and over the first metal 94 (which is alsoconductive). FIG. 4G depicts the completed first layer of the structurewhich has resulted from the planarization of the first and second metalsdown to a height that exposes the first metal and sets a thickness forthe first layer. In FIG. 4H the result of repeating the process stepsshown in FIGS. 4B-4G several times to form a multi-layer structure areshown where each layer consists of two materials. For most applications,one of these materials is removed as shown in FIG. 4I to yield a desired3-D structure 98 (e.g. component or device).

The various embodiments, alternatives, and techniques disclosed hereinmay form multi-layer structures using a single patterning technique onall layers or using different patterning techniques on different layers.For example, different types of patterning masks and masking techniquesmay be used or even techniques that perform direct selective depositionswithout the need for masking. For example, the conformable contact masksmay be used on some layers and non-conformable contact masks and maskingoperations may be used in association with the formation of otherlayers. Proximity masks and masking operations (i.e. operations that usemasks that at least partially selectively shield a substrate by theirproximity to the substrate even if contact is not made) may be used, andadhered masks and masking operations (masks and operations that usemasks that are adhered to a substrate onto which selective deposition oretching is to occur as opposed to only being contacted to it) may beused.

A first group of embodiments of the invention use diamond machining(i.e. diamond fly cutting or turning) to planarize deposits of materialsduring the electrochemical fabrication of single layer and multi-layerstructures. As diamond machining is not appropriate for effectivelymachining all materials, embodiments of the invention take on a varietyof forms with each having the common element that diamond machining willbe used during at least a portion of the planarization operationsassociated with the formation of one or more layers of a structure beingformed. Some embodiments focus on building structures using onlystructural and sacrificial materials that are readily fly cuttable. Someembodiments, focus on reducing tool wear when one or more of thebuilding materials (e.g. sacrificial materials or structural materials)are hard or difficult to machine (i.e. hard to diamond fly cut).

Many embodiments of electrochemical fabrication processes involve theuse of both a structural material and a sacrificial material. In theseembodiments, it is desired that the structural material and sacrificialmaterials meet certain criteria. For example, some common criteria forthe structural materials include: (1) desirable physical and chemicalproperties, (2) relatively low stress, (3) excellent inter-layeradhesion, (4) ability to be deposited over and adequately adhere tosacrificial material, (5) low porosity, and (6) ability to be planarizedin conjunction with neighboring regions of sacrificial material using achosen planarization process without adverse effect on the structure,excessive time and expense spent on performing the planarizationprocess, and with adequate accuracy and repeatability of the process.Some common criteria for sacrificial materials include: (1) excellentetch selectivity with respect to structural material, (2) minimalinter-diffusion with structural material prior to removal, (3) acoefficient of thermal expansion similar to that of the structuralmaterial, and (4) ability to be planarized in conjunction withneighboring regions of structural material. Of course, depending on thecircumstances, in some embodiments, it may not be necessary for each ofthese criteria, or even most of these criteria, to be met.

Certain combinations of structural and sacrificial materials have theability to be planarized using diamond machining with (1) goodplanarity, both across the wafer and locally (i.e., minimal recession ofone material vs. another), (2) minimal smearing of one material intoanother, and (3) acceptable wear of machining tools. Examples of suchmaterial combinations are set forth in Table 1: TABLE 1 StructuralMaterial Sacrificial Material Ni—P (P content Cu preferably 11% orhigher) Au Cu Cu Sn Cu Sn—Pb Au Sn Au Sn—Pb

The Ni—P may be deposited via electroless deposition orelectrolytically. If electroless Ni—P deposition is used, due topossible limitations on compatibility with some masking materials (e.g.photoresist), it may be desirable to blanket plate the Ni—P afterpattern plating of Cu. Alternatively blanket deposition of Ni—P may befollowed by selective etching of voids and then locating of sacrificialmaterial therein. To reduce material cost, in some embodiments it may bedesirable to pattern plate Au and then blanket deposit Cu. In otherembodiments, it may be possible to reduce material costs by firstselectively plating Cu then treating the Cu with one of the over-platingreduction techniques disclosed in U.S. patent application Ser. No.10/841,100, filed May 7, 2004 by Cohen, et al., and entitled“Electrochemical Fabrication Methods Including Use of Surface Treatmentsto Reduce Overplating and/or Planarization During Formation ofMulti-layer Three-Dimensional Structures”, which is hereby incorporatedherein by reference as if set forth in full.

FIG. 5A provides a flow chart of an electrochemical fabrication processthat may be followed in practicing some embodiments of the invention.The process of FIG. 5A begins with block 102 and then moves forward toblock 104 which calls for the defining of variables and parameters. Acurrent layer number variable “n” is defined, a final layer numberparameter “N” is specified, a current operation number on layer n,o_(n), is defined and for each layer n a final operation number O_(n) isdefined.

Next the process moves forward to block 106 which calls for thesupplying of a substrate on which the structure will be formed. Afterwhich the process moves forward to block 108 which calls for the settingof the current layer number variable n to 1 (n=1) one and then ontoblock 112 which calls for the setting of the current operation numbervariable o_(n) to 1 (o_(n)=1).

Next the process moves forward to decision block 114 which makes aninquiry as to whether operation on is a planarization operation. If anegative response is obtained, the process moves forward to block 116which calls for the performance of operation o_(n) and thereafter theprocess moves forward to block 140 which will be described herein later.If a positive response to the inquiry of block 114 is received, theprocess moves forward to block 118 which calls for the performance ofthe planarization operation or operations associated with the currentvalue of on and thereafter the process moves forward to block 120 whichcalls for the making of an endpoint detection measurement after whichthe process moves forward to block 124 which calls for an analysis ofthe endpoint detection data.

Next, the process moves forward to block 126 which inquires as towhether or not the planarization objective has been achieved. If theanswer to this inquiry is “no” the process moves forward to block 128which inquires as to whether additional planarization will yield thedesired objective. If the answer is “yes”, the process loops back toblock 118 where additional planarization operations will be performed,potentially using new parameters based on the fact that some amount ofplanarization has already occurred.

If block 128 produces a negative response, the process moves forward toblock 130 which calls for the taking of one of three actions. The firstof which is to institute some form of remedial action and then to jumpto any appropriate point in the process to continue structure formation.Such remedial action may include the complete removal of the currentlayer, resetting of the operation number variable and moving back toblock 114 to continue the process. Other remedial actions may involvere-depositing one or more materials and then continuing the processwhile other remedial actions may involve the recalibration or reworkingof planarization fixtures, endpoint detection fixtures, or the like.Still other remedial actions may involve redeposition of some materialand then use of a different planarization technique, such as multi-stagelapping, to replace the failed planarization technique.

A second action that may be taken may simply be to ignore the failureand continue the process as it may be determined that the failure on thegiven layer is not critical to the overall performance of the structurethat is being formed.

A third action that may be taken may involve the aborting of the processand restarting it form the beginning or redesigning the structure andthen starting the process over.

If block 126 produces a positive response, the process moves forward toblock 140 which calls for incrementing the current operation numbervariable by one and then the process moves forward to block 142 whichinquires as to whether the current operation number variable hasexceeded the final operation variable number, O_(n), for layer n. If theanswer to this inquiry is “no”, the process loops back to block 114 forthe performance of further operations on the present layer. If on theother hand this block produces a positive response, the process movesforward to block 144 which calls for the incrementing of the layernumber variable, n, by one (n=n+1) after which the process moves forwardto block 146 which inquires as to whether the current layer numbervariable, n, has exceeded the final layer number, N (n>N?). If thisinquiry produces a positive response, the process moves forward to block148 and ends. If on the other hand this inquiry produces a negativeresponse, the process loops back to block 112 where the currentoperation number is reset to one so that operations may begin forcreation of a next layer of the structure.

When block 148 is reached and the layer formation process ends, theformation of the structure may not yet be complete as various postprocessing operations may still need to occur. Such post processingoperations may include, for example: (1) heat treating of the structuresto improve interlayer adhesion, (2) release of the structure from anysacrificial material used during the layer formation process, (3) dicingof individual die regions on the substrate, (4) separation of themultiple simultaneously formed structures from the substrate on whichthey were formed, and/or (5) combining structures with other structuresfunctionally or physically to build up desired systems or devices.

FIGS. 5B and 5C provide examples of process operations that may beperformed in association with layers formed from the above notedcombinations of structural and sacrificial materials. It should beunderstood that various other process operations are possible and thatthose set forth in FIGS. 5B and 5C are just examples of two simpleversions of such processes.

The embodiment of FIG. 5B uses five operations to form a layer and insome embodiments the operations may be repeated to form additionallayers. These operations may be used in producing a desired structurewhere these operations may be plugged into the process of FIG. 5A or beused in conjunction with a different processing scheme. Block 202 setsforth the first operation which calls for the locating of a mask on asurface of the substrate or previously formed layer where the mask ispatterned so as to have openings which correspond to locations where asacrificial material is to be located. Block 204 sets forth the secondoperation which calls for the selective depositing of a diamondmachinable sacrificial material. Block 206 sets forth the thirdoperation which calls for the removal of the masking material. Block 208sets forth the fourth operation which calls for the blanket depositionof a diamond machinable structural material. Block 210 sets forth afifth operation which calls for the diamond machining of the depositedmaterials to achieve a desired planarization level (i.e. a desired netheight).

FIG. 5C sets forth operations similar to those of FIG. 5B with theexception that the structural material will be deposited first and thesacrificial material second. As a result of this change, block 222 setsforth the first operation which calls for a masking material to belocated on the surface of the substrate or previously formed layer whereopenings in the masking material correspond to locations wherestructural material is to be located. Block 224 calls for the selectivedeposition of a diamond machinable structural material. Block 226 setsforth the third operation which calls for the removal of the maskingmaterial while block 228 sets forth the fourth operation which calls forthe blanket deposition of a diamond machinable sacrificial material.Block 230, as did block 210 of FIG. 5B, calls for the diamond machiningof the deposited materials.

Some materials and material combinations are inherently unsuited forgeneral use with diamond machining but some embodiments of the inventionincorporate operations and or restrictions that minimize theincompatibilities and thus allow diamond machining to be effectivelyused in conjunction with otherwise unusable materials and materialcombinations. Materials that are typically considered incompatible withdiamond machining are Ni and Ni alloys (with the exception of Ni—P witha high percentage of P). For example, Ni and Ni—Co are difficult todiamond machine due to chemical wear of the single-point diamond tool.In the context of EFAB, several methods can be used to minimize toolwear when using difficult to machine materials, and particular whenusing them as the structural material. Operations associated with someexamples of such processes are set forth in the block diagrams of FIGS.5D-5I. Operations such as those set forth in the examples of FIGS. 5D-5Imay be implemented via a process such as that depicted in FIG. 5A orthey may be implemented using different processes. It should also beunderstood that features of the various example processes may becombined with one another and/or with other processes to derive furtherembodiments. It should also be understood that the process set forthherein to deal with difficult to machine materials may also be used inconjunction with easier to machine materials without negative effect.

Operations for a first example process where planarization of adifficult to machine material is to occur are set forth in FIG. 5D. Thefirst operation of FIG. 5D is set forth in block 242 which calls for themasking of the substrate or previously formed layer with a patternedmask having openings that correspond to locations where a first of asacrificial material or a structural material is to be located. Thesecond operation of the process is set forth in block 244 and involvesthe selective deposition of a first of the sacrificial material or thestructural material wherein at least one of the materials is hard todiamond machine. The third operation of the process is set forth inblock 246 which calls for the removal of the masking material. Thefourth operation of the process is set forth in block 248 which callsfor the blanket deposition of a second of the sacrificial material orstructural material. The fifth, and final, operation of the process isset forth in block 250 which calls for the vibration assisted diamondmachining of the deposited materials to achieve a desired planarizationlevel (i.e. net deposition height).

Use of tool vibration has been described in the literature as a means ofreducing tool wear and as a means for extending diamond machining tomaterials normally considered incapable of being diamond machined. Anexample of such a publication is “Vibration Assisted Diamond Turningusing Elliptical Tool Motion,” by Dow, T A; Cerniway, M; Sohn, A; andNegishi, N, Proceedings of the ASPE, Vol 25, November 2001, pg 92-97. Acopy of this article is set forth as Appendix A in U.S. patentapplication Ser. No. 60/534,159 which has been previously incorporatedherein by reference. In alternative embodiments, as opposed to or inaddition to using tool vibration to extend tool life, tool life may beextended by machining in an inert gas, machining in an atmospherecontaining carbon, and/or machining at cryogenic temperatures. Thesemethods may be applied to planarization operations duringelectrochemical fabrication.

Instead of trying to machine large, continuous expanses ofdifficult-to-machine (DM) material, tool wear may be decreased bymachining only small amounts of DM material (e.g. structural material)which are embedded within an easily-machined material (e.g., asacrificial material such as Cu or Sn). This result is partly due tosimply having less DM material to machine, but may also be partly due toan effect similar to that produced using tool vibration: the tool nolonger contacts DM material continuously but moves in and out of DMmaterial. The amount of time spent machining embedded DM material isdetermined by the length of the DM feature along the tool path and thetangential speed of the tool relative to the workpiece surface. The timespent can be reduced by changing either of these factors; adjusting thelength of the DM feature may impose a change on EFAB design rules. The‘duty cycle’ (the % of time the tool spends in DM vs. easily-machinedmaterial) can also be adjusted by imposing design rules on the EFABdesign and/or on the layout of die on a substrate or wafer.

The amount of time that the tool spends machining thedifficult-to-machine material may be reduced by: (1) pattern-plating theDM material and blanket plating the more easily-machined material; (2)pattern deposit both materials by either masking over the firstdeposited material or b inhibiting the deposition of the second materialonto the surface of the first deposited material by treating the surfaceof the first deposited material; (3) plating the DM material with asuniform of a thickness as possible which is not significantly greaterthan the layer thickness; (4) lapping surface of the depositions down toa level which is slightly above final desired planed level (e.g. 0.5-2microns above the target level) before diamond machining is used to cutthe remaining material down to the final desired level; (5) roughcutting (e.g., using cubic boron nitride, polycrystalline diamond,tungsten carbide) the deposited materials down to a level which isslightly above the final desired planed level before diamond machiningoccurs; (6) avoiding the existence of as much of the DM material at andabove the planarization level as possible during the time thatplanarization occurs, and/or (7) treat the surface of the hard tomachine material to make it more readily machinable, e.g. treat or dopethe surface of the hard to machine material with a second material (e.g.dope Ni with P) that changes the material properties of the firstmaterial to a depth sufficient to allow machining and, if necessary,remove any residual treatment or dopant after the machining iscompleted.

In either of techniques (4) or (5), enough material should be left abovethe final desired planarization level so that any subsurface damagecaused by lapping or rough-cutting (it is believed that suchsurface/subsurface damage can contribute to curling of layers (i.e.distortion form flatness) once the structural material is released fromthe sacrificial material. The subsurface damage caused by the initialplanarization operations may be removed by the diamond machining (whichcan produce less subsurface damage than some other methods).

An example of a process that implements the 1st technique (of reducingthe amount of time that the tool spends cutting difficult to machinematerial) is set forth in the operations of FIG. 5E. Operation 1 of FIG.5E is set forth in block 250 and calls for the masking of the surface ofthe substrate or previously formed layer with a patterned mask that hasopenings which correspond to locations where a first of a sacrificialmaterial or a structural material is to be located. Operation 2 is setforth in block 264 and calls for the selective deposition of a hard tomachine selected one of the sacrificial material or structural material.Operation 3 is set forth in block 266 and calls for the removal of themasking material. Operation 4 is set forth in block 268 and calls forthe blanket deposition of the non-selected one of the structuralmaterial or sacrificial material which is not hard or difficult tomachine. The 5th, and final, operation of the example process is setforth in block 270 and calls for the diamond machining of the depositedmaterials to achieve a desired level of planarized material.

Numerous variations of these operations are possible and will beapparent to those of skill in the art upon reviewing the teachings setforth herein. For example, the blanket deposition of Operation 4 may bereplaced by a selective deposition operation. As another example, insome implementations the selected deposition of Operation 2 may bereplaced by a blanket deposition and a subsequent selective etchingoperation. As a third example the two depositions of Operations 2 and4may be implemented, for example, via electroplating operations,electroless plating operations, or a combination thereof. As a fourthexample, if one of the materials is a dielectric material, appropriateapplication of one or more seed layer materials may be utilized ifnecessary.

An example of a process that implements the 4th technique (for reducingthe amount of time that the tool spends cutting difficult to machinematerial) is set forth in the operations of FIG. 5F. FIG. 5F sets forthsix operations that may be used in forming one or more layers of astructure. The 1 st operation is set forth in block 282 which calls forthe masking of the surface of the substrate or previously formed layerwith a patterned mask that has openings which correspond to locationswhere a selected one of a sacrificial material or structural material isto be located. Operation 2 is set forth in block 284 which calls for theselective deposition of a hard to machine selected one of thesacrificial or structural materials. The 3rd operation is set forth inblock 286 which calls for the removal of the masking material. The 4thoperation is set forth in block 282 and calls for the blanket depositionof the non-selected one of the structural and sacrificial materials. Inthis embodiment, it is assumed that the non-selected one of thematerials is not hard or difficult to machine.

The 5th operation is set forth in block 290 which calls for using one ormore lapping or rough cutting operations to trim the thickness of thedeposits to within a small increment of a desired planarization level.The rough cutting operations, if used, may be based on using machinetool tips of cubic boron nitride, polysilicon diamond, or tungstencarbide, for example. The 6th operation is set forth in block 292 whichcalls for the diamond machining of the thinned down deposited materialssuch that a desired height of deposition (i.e. surface level) isachieved. As with the other sets of operations set forth herein,numerous variations of the operations described in this example arepossible.

An example of a process that implements a variation of the 4th technique(of reducing the amount of time that the tool spends cutting difficultto machine material) is an embodiment that includes the formation of astructure from three-materials as set forth in the operations of FIG.5G. The layer formation operations of FIG. 5G include ten separateoperations. The 1 st of which is set forth in block 322 which calls forthe masking of the surface of the substrate or previously formed layerwith a patterned mask having openings which correspond to locationswhere a hard to machine structural material is to be located. The 2ndoperation of the process is set forth in block 324 which calls for theselective deposition of the structural material onto the substrate orpreviously formed layer via the openings in the mask. The 3rd operationof the process is set forth in block 326 which calls for the removal ofthe masking material. The fourth operation of the process is set forthin block 328 which calls for the blanket deposition of a sacrificialmaterial. The 5th operation of the process is set forth in block 330which calls for the lapping or rough cutting of the deposited materialsto a level which is above, or short of, the ultimate planarization levelfor the layer. The planarization done in Operation 5 serves twopurposes, one of which is the minimization of the thickness of the hardto machine material that will eventually be planarized using diamondmachining and the other of which is the obtainment of a uniform workingsurface on which subsequent operations may be performed.

The 6th operation is set forth in block 332 which calls for the maskingof the surface of one or both of the deposited materials with apatterned mask that has openings which correspond to locations where a3rd material is to be located. In some variations of this process theopenings may be made to occur over regions which previously receivedstructural material only while in other variations the openings may belocated over some regions that received structural material and otherregions that received sacrificial material, while in still furthervariations the openings may be located over regions occupied bypreviously deposited sacrificial material only. In the present exampleit is assumed that the openings in the mask are located only aboveregions where sacrificial material was deposited.

The 7th operation of the process is set forth in block 334 which callsfor the etching of openings into the sacrificial material to a depthwhich is the sum of the layer thickness plus an incremental tolerancebased amount, δ, and an amount which is based on the difference betweenthe rough cut planarization level and the final desired planarizationlevel. The amount δ is set large enough to ensure that the bottom of thelayer is reached but not so large that a void is inadvertently formedthat extends an undesirable amount into a previous layer.

The 8th operation of this example is set forth in block 336 which callsfor the selective deposition of a third material into the openings thathave been etched into the sacrificial material. In the present example,it is assumed that the 3rd material is a material that is not difficultto machine. The 9th operation of the process is set forth in block 338which calls for the removal of the masking material. The 10th operationof this example is set forth in block 340 which calls for the diamondmachining of the deposited materials to achieve a desired net height ofdeposition (i.e. a desired planarization level).

An example of a process that implements a variation of the 4th technique(of reducing the amount of time that the tool spends cutting difficultto machine material) is an embodiment that includes the formation of astructure from three-materials (one of which is a dielectric material)as set forth in the operations of FIG. 5H. The example of FIG. 5H setsforth a twelve operation layer formation process which includes a roughcutting planarization operation and a diamond machining operation andwhich also includes the deposition of three materials, one of which is asacrificial material.

The 1 st operation of this example is depicted in block 362 which callsfor the masking of the substrate or previously formed layer with apatterned mask having openings which correspond to locations where aconductive, hard to machine structural material is to be located.

The 2nd operation of this example is set forth in block 364 which callsfor making a determination as to whether the substrate or previouslyformed layer is adequately conductive to allow deposition of thestructural material. If it is determined that the substrate orpreviously formed layer is not adequately conductive a seed layer of aselected material and if necessary an adhesion layer of a selectedmaterial may be applied. If it is determined that the structural layeris adequately conductive the process proceeds to the 3rd operation.

The 3rd operation of the process is set forth in block 366 which callsfor the selective deposition of a conductive structural material. The4th operation of the process is set forth in block 368 which calls forthe removal of the masking material.

The 5th operation of the process is set forth in block 370 which issimilar to the second operation of the process as it calls for adetermination of whether the exposed portions of the substrate orpreviously formed layer are adequately conductive to receive a depositof a conductive sacrificial material. If it is determined that thesubstrate or previously formed layer is not adequately conductive then aseed layer of a selected material and if necessary an adhesion layer ofa selected material may be applied. If it is determined that thestructural layer is adequately conductive the process proceed to the 6thoperation.

The 6th operation of the process is set forth in block 372 which callsfor the blanket deposition of the conductive sacrificial material. The7th operation of the process calls for the lapping or rough cutting ofthe deposited materials to a level that is above the desired level forthe completed layer by a desired amount z.

The 8th operation of this example is set forth in block 384 which callsfor the masking of the surface of the deposited materials with apatterned mask having openings that correspond to locations where adielectric 3rd material is to be located. As with Operation 6 of FIG. 5Gas set forth in block 332 the masking of this operation (Operation 8)and variations of this example may locate openings above the sacrificialmaterial, the structural material, or a combination of both. In thepresent example it is assumed that the openings are located only overregions of sacrificial material. It is worth noting that in the presentexample, as well as in the example of FIG. 5F, as a selective etchingoperation is to be performed in the operation which is subsequent to themasking operation it may not be necessary that the openings in themasking material identically correspond to regions to be etched if suchregions are in whole or in part bounded by material that will not beattacked by the particular etchant utilized. As such, in some variationsof these examples it may be possible to use masks that deviate fromexact etching patterns in certain ways.

Operation 9 of the present example is set forth in block 386 which callsfor the etching of openings into the sacrificial material where theopenings are etched to a depth equal to the layer thickness plus theamount z plus an incremental amount δ (LT+z+δ). The incremental amountmay be associated with a tolerance, or uncertainty, in the exactseparation between the upper surface being etched and the location ofthe bottom of the layer.

Operation 10 is set forth in block 388 which calls for the selectivedeposition of a 3rd material into the openings that were etched into thesacrificial material.

The 11th operation of this example is set forth in block 390 which callsfor the removal of the masking material which was applied in Operation8.

The 12th, and final, operation of this example calls for diamondmachining of the deposited materials to achieve a desired planarizationlevel (i.e. a bounding level for the present layer).

As with the other examples set forth herein numerous variations arepossible and will be understood by those of skill in the art afterstudying the teachings set forth herein. Two such variations may bebased on the use of either the 1st masking material applied in Operation1 or the 2nd masking material applied in Operation 8 as one of thebuilding materials from which layers are to be built up.

The avoidance approach of the 6th technique may be implemented in avariety of different ways, for example, a first implementation mightinvolve depositing the DM material (i.e. difficult to machine material)in all desired locations to an approximately uniform depth and thenselectively etching into selected regions (e.g. regions which will beoverlaid by the DM material deposited in association with the formationof the next layer). The depth of etching preferably extends at least anincremental amount below the final desired planarization level such thatDM material in that portion of the cross-section never undergoesplanarization. During continued formation of the layer, if desired, theetched openings may be filled in with an easy to planarize material.Then during formation of a next layer the opening may be etched free ofthe easy to planarize material and the difficult-to-planarize materialmay be deposited to fill the voids while it is being deposited todesired locations associated with the next layer. In anotheralternative, it may not be necessary to back fill the voids prior toplanarization as any surface oddities that result near the edge of anunfilled void may simply be hidden by the deposition associated withformation of the next layer. Alternatively to avoid undesired overfilling of some areas, the filling of the opening and the depositing ofthe DM for the next layer may be performed in separate selective fillingoperations. In still other alternatives, the openings filled with themore easily machinable material may remain filled with the easilymachinable material which may simply become trapped therein as a resultof depositing the DM material in association with the next layer.

An example of a process that provides an implementation of the 6thtechnique is set forth in the operations of FIG. 5I. This example alsoimplements a two step planarization process of the 4th technique. Theexample of FIG. 5I reduces tool wear by (1) using a lapping operation orinitial rough cutting operation to trim a thickness of depositedmaterial to a level which is closer to a final desired planarizationlevel and (2) using an etching operation to remove portions of thedifficult to machine material from regions where planarization willoccur. The layer formation process of FIG. 5I includes nine operations.

The first operation is set forth in block 302. This first operation is aconditional operation which indicates that if regions of hard to machinematerial on the previous layer are temporarily occupied by a not hard tomachine material then the surface of the previous layer should be maskedsuch that some regions of the layer are shielded and such that openingsexist in the masking material which leave those regions exposed wherethe temporarily located, not hard to machine material is to be removed.The operation also calls for the etching away of the not hard to machinematerial from those temporary locations.

The second operation of the process is set forth in block 304 and callsfor the masking of the substrate or previously formed layer with apatterned mask that has openings which correspond to locations where aselected one of a sacrificial material or structural material is to belocated.

The third operation is set forth in block 306 which calls for theselective deposition of a hard to machine selected one of thesacrificial material or structural material (i.e. the material for whichopenings were made in the mask of Operation 2).

The fourth operation is set forth in block 308 which calls for theremoval of the masking material.

The fifth operation of the process is set forth in block 310 which callsfor the application of a second mask which includes openings that exposeselected regions of the hard to machine material that will exist on thenext layer. The regions that are to be etched are those which representthe bulk of the intersection regions between locations of hard tomachine material on the present layer and hard to machine material onthe next layer. Though in some implementations it may be acceptable toetch boundary portions of the intersecting regions, in otherimplementations it is preferred that boundary portions of theintersecting regions not be subjected to etching.

The sixth operation of the process is set forth in block 312 which callsfor the etching of the exposed regions of the hard to machine materialso as to reduce them to a height which locates their upper surfacesbelow the planarization level that is to be achieved.

The seventh operation is set forth in block 314 which calls for theblanket deposition of the non-selected one of the structural materialand sacrificial material. In this process it is assumed that thisnon-selected material is not hard or difficult to machine.

The eighth operation of the process is set forth in block 316 while theninth operation is set forth in block 318. Blocks 316 and 318,respectively, call for the lapping or rough cutting of the depositedmaterials and then the diamond machining of the remaining material totrim the deposit height to the desired planarization level. Theoperations of blocks 316 and 318 are analogous to those set forth inblock 290 and 292 respectively of FIG. 5F. As a result of the etchingoperations of this embodiment there was less of the difficult to machinematerial present during diamond machining operations and thus less toolwear. Furthermore, due to the fact the etched regions representedintersections between regions on the present layer with those on thenext layer, the etched regions will be filled in with the commonmaterial during formation of the next layer without any loss ofstructural accuracy but possibly with an enhancement in structuralintegrity.

A second implementation may involve the dispensing of the hard tomachine material in a two step process, e.g. deposit all desiredlocations to a first height (which extends to a level below that of thefinal desired planarization level), and then in a second deposit buildup the height of deposition in selected locations. Alternatively,deposit selected locations to a final desired height and then depositother selected locations to a different final desired height, where oneof the heights locates material at or above the desired layer level andthe other locates material below the height of the layer level.

A third implementation may involve modifying the data representing thethree-dimensional structure so as to define it as a shell or envelop ofdifficult-to-machine structural material that encapsulates aneasy-to-machine material. Alternatively, the structure may be defined asan envelope of structural material that surrounds an internal grid ofstructural material with intermediate regions of sacrificial material.FIG. 6 sets forth a block diagram of this third implementation of the₆th approach.

Various other embodiments of the present invention exist. Some of theseembodiments may be based on a combination of the teachings herein withvarious teachings incorporated herein by reference. Some embodiments maynot use any blanket deposition processes. Some embodiments may involvethe selective deposition of a plurality of different materials on asingle layer or on different layers. Some embodiments may use selectivedeposition processes or blanket deposition processes on some layers, oron all layers, that are not electrodeposition processes. Someembodiments may use nickel as a structural material while otherembodiments may use different materials. Some embodiments may use copperas the structural material with or without a sacrificial material. Someembodiments may remove a sacrificial material while other embodimentsmay not include use of a sacrificial material but instead use two,three, or more structural materials in forming each layer. For example,in some embodiments, two materials may be deposited per layer and bothmay be structural materials (e.g. one may be a dielectric of thepolymeric, oxide, or ceramic type while the other is a conductivematerial). In some alternative embodiments, diamond fly cuttingplanarization operations may be replaced with fly cutting operationsbased on other tool materials. In some embodiments, selectivedepositions of conductive and or dielectric materials may occur withoutusing masks but instead using direct writing techniques.

As noted previously, in some of the implementations set forth above, theelectrochemical fabrication methods set forth herein may involve the useof selective etching operations to minimize the amount ofdifficult-to-machine material that is encountered by diamond machiningoperations. As noted above some embodiments may form structures on alayer-by-layer basis but deviate from a strict planar layer on planarlayer build up process in favor of a process that interlacing materialbetween the layers. Such alternating build processes are more fullydisclosed in U.S. application Ser. No.10/434,519, filed on May 7, 2003,entitled “Methods of and Apparatus for Electrochemically FabricatingStructures Via Interlaced Layers or Via Selective Etching and Filling ofVoids” which is herein incorporated by reference as if set forth infull.

The techniques disclosed herein may be combined with the techniquesdisclosed in the following patent applications which are focused on theformation of structures on dielectric substrates and/or the formation ofstructures that incorporate dielectric materials during the formationprocess and possibility into the final structures as formed. The firstof these applications is U.S. patent application Ser. No. 60/534,184,which is entitled “Electrochemical Fabrication Methods IncorporatingDielectric Materials and/or Using Dielectric Substrates”. The second ofthese applications is U.S. patent application Ser. No. 60/533,932, whichis entitled “Electrochemical Fabrication Methods Using DielectricSubstrates”. The third of these applications is U.S. patent applicationSer. No. 60/534,157 which is entitled “Electrochemical FabricationMethods Incorporating Dielectric Materials”. The fourth of theseapplications is U.S. patent application Ser. No. 10/841,300, which isentitled “Methods for Electrochemically Fabricating Structures UsingAdhered Masks, Incorporating Dielectric Sheets, and/or Seed layers ThatAre Partially Removed Via Planarization”. The fifth of theseapplications is U.S. patent application Ser. No.10/841,378, which isentitled “Electrochemical Fabrication Method for Producing Multi-layerThree-Dimensional Structures on a Porous Dielectric”. These patentapplications are each hereby incorporated herein by reference as if setforth in full herein.

The planarization techniques disclosed herein may be combined withplanarization end point detection and parallelism maintenance techniquesdisclosed in U.S. patent application Ser. No. XX/XXX,XXX (correspondingto Microfabrica Docket No. P-US132-A-MF) which is being filedconcurrently herewith by Cohen et al. and which is entitled “Method andApparatus for Maintaining Parallelism of Layers and/or Achieving DesiredThicknesses of Layers During the Electrochemical Fabrication ofStructures”. This referenced application is incorporated herein as ifset forth in full herein.

Due to the reduction in smearing that may result from use of diamondmachining as opposed to lapping, electrochemical fabrication processesthat form structures from materials with greatly differing hardness maybenefit from the use of diamond lapping in the performance of at leastsome planarization operations. Some such variations in hardness mayexist in embodiments where dielectric materials will be used along withmetals.

Microprobe arrays (i.e. arrays of compliant electronic contact elements)may represent a viable application for the use of diamond machining. HMmaterials may be incorporated into the probe arrays as individual probeelements that, in many cases, have relatively small regions of HMstructural material surrounded by relatively large regions ofsacrificial materials. Further teaching about microprobes andelectrochemical fabrication techniques are set forth in a number of USPatent Applications. These applications include: (1) U.S. patentapplication Ser. No. XX/XXX,XXX (corresponding to Microfabrica DocketNo. P-US129-A-MF) by Chen, et al., filed concurrently herewith, andentitled “Vertical Microprobes for Contacting Electronic Components andMethod for Making Such Probes”; (2) U.S. patent application Ser. No.60/533,975, filed Dec. 31, 2003, by Kim et al. and which is entitled“Microprobe Tips and Methods for Making”; (3) U.S. patent applicationSer. No. 60/533,947, by Kumar et al., filed Dec. 31, 2003, and which isentitled “Probe Arrays and Method for Making”; (4) U.S. patentapplication Ser. No. 60/533,948 by Cohen et al., filed Dec. 31, 2003 andwhich is entitled “Electrochemical Fabrication Method for Co-FabricatingProbes and Space Transformers”; and (5) U.S. patent application Ser. No.60/533,897, filed Dec. 31, 2004, by Cohen et al. and which is entitled“Electrochemical Fabrication Process for Forming MultilayerMultimaterial Microprobe structures”. These patent filings are eachhereby incorporated herein by reference as if set forth in full herein.

In view of the teachings herein, many further embodiments, alternativesin design and uses of the instant invention will be apparent to those ofskill in the art. As such, it is not intended that the invention belimited to the particular illustrative embodiments, alternatives, anduses described above but instead that it be solely limited by the claimspresented hereafter.

1. A fabrication process for forming a multi-layer three-dimensionalstructure, comprising: (a) forming and adhering a layer of material to apreviously formed layer and/or to a substrate, wherein the layercomprises a desired pattern of at least one material, wherein one ormore contact pads exist on the substrate or on a previously formedlayer; (b) subjecting the at least one material to a planarizationoperation which comprises diamond machining (c) repeating the formingand adhering of operation (a) one or more time to form thethree-dimensional structure from a plurality of adhered layers.
 2. Theprocess of claim 1 wherein forming and adhering of the layer of materialinvolves the deposition of a first material and followed by depositionof a second material wherein at least one of the first or secondmaterials is deposited via an electroplating operation.
 3. The processof claim 2 wherein the first and second materials comprise Ni—P and Cu.4. The process of claim 2 wherein the first and second materialscomprise Au and Cu.
 5. The process of claim 2 wherein the first andsecond materials comprise Cu and Sn.
 6. The process of claim 2 whereinthe first material is more difficult to machine than the secondmaterial.
 7. The process of claim 2 wherein the first material is astructural material and wherein the second material is a sacrificialmaterial.
 8. The process of claim 2 wherein the structure comprises anenvelope of structural material surrounding an entrapped quantity ofsacrificial material, wherein the structural material is more difficultto machine using diamond machining than the sacrificial material.
 9. Theprocess of claim 2 wherein the structure comprises an envelope ofstructural material surrounding an entrapped quantity of sacrificialmaterial, wherein the structural material is more difficult to machineusing diamond machining than the sacrificial material.
 10. The processof claim 9 wherein the envelope of structural material also surrounds agrid of structural material.
 11. The process of claim 2 wherein theplanarization operation additionally comprises vibration assistedmachining.
 12. The process of claim 2 wherein prior to subjecting thedeposited material to the planarization operation, the first depositedmaterial is subjected to a selective etching operations that removes aportion of the first material to a level below a final desiredplanarization level in regions where the etched first material will beoverlaid by first material deposited in association with the next layer.13. The process of claim 1 wherein forming and adhering of the layer ofmaterial involves the deposition of a first material, followed bydeposition of a second material, and followed by deposition of at leasta third material wherein at least one of the first, second, or thirdmaterials is deposited via an electroplating operation.
 14. The processof any of the preceding claims wherein the planarization operationincludes at least one lapping operation or rough cutting operation thatbrings height of deposition to a level which is closer to that of thefinal desired level and after which the diamond machining operationbrings the level of the deposited materials to a level that is within adefined tolerance of a desired level.
 15. The process of claim 14wherein the lapping or rough cutting substantially planarizes thesurfaces and where a difference between the material surface subjectedto the lapping or rough cutting is spaced from the final desiredplanarization level by an amount which is equal to or greater than adepth to which the lapping or rough cutting causes subsurface damage.